<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>后盾人</title>
  </head>
  <body>
    <div id="app">
      <div class="houdunren" data="hd">houdunren.com</div>
      <div class="hdcms">hdcms.com</div>
      <div class="xiangjun"><!-- 向军大叔 --></div>
    </div>
    <script>
      let app = document.getElementById('app')
      console.log(app.nodeType)

      console.log(app.firstChild.nodeType)

      console.log(app.childNodes[1].attributes[0].nodeType)

      const xj = document.querySelector('.xiangjun')
      console.log(xj.firstChild.nodeType)

      console.dir(app)

      console.log(app instanceof HTMLDivElement)

      console.log(app instanceof Element)
    </script>
  </body>
</html>
